package cn.mengmei.cookie;
import java.io.IOException;
import java.util.Date;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CookieDemo1 extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//获取浏览器带过来的名为lastDate的Cookie
Cookie[] cookies = request.getCookies();
String lastDate = "";
if(cookies != null){
for(Cookie cook : cookies){
if(cook.getName().equals("lastDate")){
lastDate = cook.getValue();
}
}
}
//将时间打印到浏览器显示
response.setContentType("text/html;charset=UTF-8");
response.getWriter().write("上次访问时间:"+lastDate);
//最新时间值
String newTime = new Date(System.currentTimeMillis()).toLocaleString();
//将当前时间封装到Cookie,设置有效期为30天。
Cookie cookie = new Cookie("lastDate", newTime);
cookie.setMaxAge(30*24*3600); //设置为0,可以将该Cookie从硬盘删掉。
//没有设置有效path,默认是本Servlet所在目录: /myday07/servlet
//必须在本Servlet所在目录 /myday07/servlet 下的Servlet才能够将此Cookie删除。
//假如你在这里设置了有效目录,那么在你删的时候也必须设置相同的有效目录才能够删除。
//将Cookie打给浏览器
response.addCookie(cookie);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
第一次访问没有时间值,第二次访问显示第一次访问的时间,浏览器关掉再打开还能显示:
上次访问时间:2015-2-12 23:05:23
实现过程:
显示商品列表的首页Servlet:
package cn.mengmei.cookie;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MainServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
//联合使用以下三个响应消息头,控制浏览器不要缓存。
response.setHeader("Expires", "-1");
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");
PrintWriter out = response.getWriter();
out.write("JSP教程 张孝祥
");
out.write("HTML+CSS+JS 雷拓
");
out.write("JAVA就业教程 王山海
");
out.write("structs框架从入门到精通
");
out.write("Windows编程 MFC
");
out.write("您最近浏览过的历史记录:
");
Cookie[] cookies = request.getCookies();
if(cookies!=null){
for(Cookie cook : cookies){
if(cook.getName().equals("bookHistory")){
String history = cook.getValue();
String[] ids = history.split(",");
for (String id : ids) {
switch (id) {
case "1":
out.write("JSP教程 张孝祥
");
break;
case "2":
out.write("HTML+CSS+JS 雷拓
");
break;
case "3":
out.write("JAVA就业教程 王山海
");
break;
case "4":
out.write("structs框架从入门到精通
");
break;
case "5":
out.write("Windows编程 MFC
");
break;
default:
break;
}
}
}
}
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
详细页面:
package cn.mengmei.cookie;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.LinkedList;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DetailServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
String id = request.getParameter("id");
boolean flag = true;
Cookie[] cookies = request.getCookies();
if(cookies!=null){
for(Cookie cook : cookies){
if(cook.getName().equals("bookHistory")){
flag = false;
String history = cook.getValue();
if(!history.contains(id)){
StringBuilder sb = new StringBuilder(history);
sb.insert(0, id+",");
history = sb.toString();
System.out.println(history);
cook.setValue(history);
cook.setMaxAge(30*24*3600);
response.addCookie(cook);
}else{
history = history.replaceAll("["+id+"]", "");
StringBuilder sb = new StringBuilder(history);
sb.insert(0, id+",");
history = sb.toString();
history = history.replaceAll("\\W*(\\W{1})", "$1");
while(history.startsWith(",")){
history = history.substring(1);
}
while(history.endsWith(",")){
history = history.substring(0, history.length()-1);
}
System.out.println(history);
cook.setValue(history);
cook.setMaxAge(30*24*3600);
response.addCookie(cook);
}
}
}
if(flag){
Cookie cookie = new Cookie("bookHistory", id);
cookie.setMaxAge(30*24*3600);
response.addCookie(cookie);
}
}else{
Cookie cookie = new Cookie("bookHistory", id);
cookie.setMaxAge(30*24*3600);
response.addCookie(cookie);
}
PrintWriter out = response.getWriter();
switch (id) {
case "1":
out.write("JSP教程 张孝祥---详细信息页面。。。。。。。。。。。");
break;
case "2":
out.write("HTML+CSS+JS 雷拓---详细信息页面。。。。。。。。。。。");
break;
case "3":
out.write("JAVA就业教程 王山海---详细信息页面。。。。。。。。。。。");
break;
case "4":
out.write("structs框架从入门到精通---详细信息页面。。。。。。。。。。。");
break;
case "5":
out.write("Windows编程 MFC---详细信息页面。。。。。。。。。。。");
break;
default:
break;
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
效果:
老师讲的标准代码:
package cn.mengmei.cookie;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MainServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//显示商品列表
response.setContentType("text/html;charset=UTF-8");
response.setHeader("Expires", "-1");
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");
PrintWriter out = response.getWriter();
out.write("首页图书展示:
");
Map map = DB.getAll();
Set> set = map.entrySet();
for(Map.Entry me : set){
Book book = me.getValue();
String name = book.getName();
String id = book.getId();
out.write(""+name+"
");
}
out.write("
");
//最近浏览
out.write("最近浏览:
");
Cookie[] cookies = request.getCookies();
String bookHistory = null;
for(int i=0; cookies!=null && i ");
}
}
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
class DB{
private static Map map = new LinkedHashMap();
static{
map.put("1", new Book("1","javaweb教程","张孝祥","一本好书!"));
map.put("2", new Book("2","structs精通","黎活明","很棒!"));
map.put("3", new Book("3","Hibernate教程","方立勋","哈哈好书!"));
map.put("4", new Book("4","Spring讲解","刘云山","好书书书!"));
}
public static Map getAll(){
return DB.map;
}
}
class Book{
private String id;
private String name;
private String author;
private String descrip;
public Book() {
super();
}
public Book(String id, String name, String author, String descrip) {
super();
this.id = id;
this.name = name;
this.author = author;
this.descrip = descrip;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
public String getDescrip() {
return descrip;
}
public void setDescrip(String descrip) {
this.descrip = descrip;
}
}
package cn.mengmei.cookie;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.LinkedList;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DetailServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//根据id显示商品详细信息
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
out.write("商品详细:
");
String id = request.getParameter("id");
Book book = (Book) DB.getAll().get(id);
out.write("id:"+book.getId()+"
");
out.write("书名:"+book.getName()+"
");
out.write("作者:"+book.getAuthor()+"
");
out.write("描述:"+book.getDescrip()+"
");
//给浏览器端发送Cookie
Cookie cookie = new Cookie("bookHistory", makeHistory(request,id));
cookie.setMaxAge(30*24*3600);
response.addCookie(cookie);
}
private String makeHistory(HttpServletRequest request, String id) {
Cookie[] cookies = request.getCookies();
String bookHistory = null;
for(int i=0; cookies!=null && i link = new LinkedList();
if(bookHistory != null){
String[] ids = bookHistory.split("\\_");
link.addAll(Arrays.asList(ids));
if(link.contains(id)){
link.remove(id);
}
link.addFirst(id);
while(link.size() > 3){
link.removeLast();
}
}else{
link.add(id);
}
StringBuilder sb = new StringBuilder();
for(String i : link){
sb.append(i+"_");
}
sb.deleteCharAt(sb.length()-1);
return sb.toString();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}